Gas generator for air bag and air bag device

ABSTRACT

In a gas generator for an air bag, there is provided a gas generator in which an operating performance is improved. A porous tube member, in which a portion crossing the ejecting direction of a flame and the like generated due to an activation of ignition means stored in an inner cylindrical member is formed as a flame-preventing annular portion having no opening, is arranged in a gas generator housing. Further, there is provided a multistage type gas generating apparatus which prevents an erroneous connection between a plurality of igniters  8  stored in a gas generator  1  and outputting portions  7  of an ignition signal outputting device  2.  In the multistage type air bag apparatus, the gas generator includes a plurality of igniters  8,  and a defining means  17  for specifying the unique connection between the respective ignition signal outputting means and the respective igniters  8  is provided in a connector  10  provided in a lead wire  9  for sending an ignition signal to each of the igniters  8.

TECHNICAL FIELD

[0001] The present invention relates to a gas generator for an air bag preferably used for an air bag which is placed in a vehicle to protect the occupant from the impact, and an air bag system using the same.

PRIOR ART

[0002] An air bag apparatus is mounted to an automobile or the like in order to protect the occupant from the impact at a time of collision. The air bag apparatus comprises a sensor, a control unit, a pad module and the like. The pad module is mounted, for example, to a steering wheel, and is constituted by a module case, an air bag, a gas generator and the like.

[0003] Among the above, the gas generator is structured such that when an ignition means is activated by the impact, a gas generating means is burned to generate a gas having a high temperature and a high pressure, and the generated gas is ejected into an air bag (bag body) from a gas discharge port to expand the air bag. This expanded air bag forms a cushion for absorbing the impact between the steering wheel and the occupant, thereby protecting the occupant from the impact.

[0004] In conventional gas generators, as an ignition means for igniting the gas generating means, for example, there has been used a combination between an electrical ignition type igniter activated by the inputted activation signal and a transfer charge arranged in the vicinity of this igniter and ignited by the activated igniter so as to burn. The transfer charge ignited and burned due to the activation of the igniter generates a flame and/or a heat, thereby igniting and burning the gas generating means.

[0005] Meanwhile, a space (that is, a combustion chamber) in which the gas generating means is stored is variously designed in correspondence to a shape of a housing, an arrangement of required constituting members and the like, and various kinds of shapes, components or the like are employed for the gas generating means charged therein.

[0006] Then, since a combustion condition of the gas generating means can be an important element for adjusting an operating performance of the gas generator, it is desirable that the gas generating means charged within the combustion chamber is effectively and unfailingly ignited and burned on the basis of the activation of the ignition means.

[0007] However, in conventionally proposed gas generators, in view of improving the igniting property of the gas generating means, there is still room for improvement.

DISCLOSURE OF THE INVENTION

[0008] Accordingly, the present invention provides a gas generator for an air bag in which an operating performance is improved. Further, by providing a structure which can improve an ignition of gas generating means, there is provided a gas generator in which an operating performance is improved.

[0009] A gas generator for an air bag according to the present invention is characterized in which a porous cylindrical member having a specific structure inside of filter means.

[0010] According to the present invention, there is provided a gas generator for an air bag in which an inner cylindrical member is arranged in a cylindrical housing having a gas discharge port to define the inner space of the housing,

[0011] an ignition means including an igniter activated by the activation signal and generating flame and/or heat upon the activation of the igniter is arranged inside of the inner cylindrical member,

[0012] a combustion chamber storing a gas generating agent ignited and burned by the flame and/or the heat generated by the ignition means to generate a combustion gas is provided outside the inner cylindrical member in the radial direction, and

[0013] a cylindrical filter means for cooling and/or purifying the combustion gas is arranged outside the combustion chamber in the radial direction,

[0014] wherein the ignition means is stored in a ignition means accommodating chamber defined in the inner cylindrical member,

[0015] aflame-transferring hole for flowing the flame and/or the heat, which is generated in the ignition means storing chamber due to the activation of the ignition means, into the combustion chamber is formed in the inner cylindrical member,

[0016] a porous tube member having a plurality of openings is arranged in the filter means in the radial direction, and

[0017] in the porous tube member, at least a portion crossing the ejecting direction of the flame and/or the heat of the ignition means ejected from the flame-transferring hole is formed as a flame-preventing annular portion having no opening.

[0018] Further, according to the present invention, there is provided a porous tube member used in a gas generator for an air bag in which an inner cylindrical member is arranged in a cylindrical housing having a gas discharge port to define the inner space of the housing,

[0019] an ignition means activated upon the impact to generate flame and/or heat is arranged in the inner cylindrical member,

[0020] a combustion chamber is provided outside the inner cylindrical member in the radial direction to store a gas generating agent ignited and burned by the flame and/or the heat of the ignition means ejected from a flame-transferring hole provided in a circumferential wall of the inner cylindrical member, and

[0021] a cylindrical filter means for cooling and/or purifying the combustion gas generated due to the combustion of the gas generating agent is arranged outside the combustion chamber in the radial direction,

[0022] wherein the porous tube member has a shape capable of being arranged opposite to an inner peripheral surface of the cylindrical coolant/filter means, and at least a portion crossing the ejecting direction of the flame and/or the heat of the ignition means ejected out from the flame-transferring hole is formed as a flame-preventing annular portion having no opening.

[0023] Further, according to the present invention, there is provided an air bag apparatus comprising:

[0024] the gas generator for the air bag;

[0025] an impact sensor detecting the impact to activate the gas generator;

[0026] an air bag introducing therein a gas generated in the gas generator to inflate; and

[0027] a module case accommodating the air bag.

[0028] In particular, according to the present invention, there is provided a porous tube member used in a gas generator for an air bag in which an inner cylindrical member is arranged in a cylindrical housing having a gas discharge port to concentrically define the inner space of the housing, an ignition means including an igniter activated by the activation signal to generate flame and/or heat due to an activation of the igniter is arranged in the inner cylindrical member, a combustion chamber for storing a gas generating agent ignited and burned by the flame and/or the heat generated by the ignition means to generate a combustion gas is provided outside the inner cylindrical member in the radial direction, and a cylindrical filter means for cooling and/or purifying the combustion gas is arranged outside the combustion chamber in the radial direction,

[0029] wherein the ignition means is stored in an ignition means accommodating chamber defined in the inner cylindrical member,

[0030] a flame-transferring hole for flowing the flame and/or the heat, which is generated in the ignition means accommodating chamber due to the activation of the ignition means, into the combustion chamber is formed in the inner cylindrical member,

[0031] a porous tube member having a plurality of openings is arranged inside the filter means in the radial direction, and

[0032] in the porous tube member, at least a portion crossing the ejecting direction of the flame and/or the heat of the ignition means ejected from the flame-transferring hole is formed as a flame-preventing annular portion.

[0033] In this gas generator, when the frame, the hot gas and the mist (hereinafter, referred to as the “flame and the like of the ignition means”) which are generated due to the activation of the ignition means flow into the combustion chamber through the flame-transferring hole formed in the inner cylindrical member, the flame and the like of the ignition means strikes the flame-preventing annular portion of the porous tube member arranged inside the filter means and the direction thereof is changed. Consequently, the flame and the like of the ignition means spreads the entire interior of the combustion chamber so that all gas generating agent in the combustion chamber can be ignited and burned, whereby improving an ignition of the gas generating agent. Further, since the flame and the like of the ignition means ejected from the flame-transferring hole is not directly ejected over the filter means, a possibility of erosion or the like of the filter means can be omitted.

[0034] Further, in the gas generator for an air bag of the present invention, a second combustion chamber adjacent to the ignition means accommodating chamber in the axial direction, separated from the ignition means accommodating chamber by a partition wall and storing a second gas generating agent is provided in the cylindrical member, and a combustion gas generated due to a combustion of the second gas generating agent flows into the combustion chamber (a first combustion chamber) provided outside the inner cylindrical member in the radial direction through a through-hole formed in a circumferential wall of the inner cylindrical member. Further, in this gas generator, at least a portion in the porous tube member which crosses the direction of the combustion gas generated due to the combustion of the second gas generating agent ejected from the through-hole is formed as a porous annular portion having a plurality of openings.

[0035] In particular, in the case of the gas generator in which the (second) combustion chamber is formed inside the inner cylindrical member as mentioned above, the (first) combustion chamber provided outside the inner cylindrical member may be formed to have a small radial distance in correspondence to a size of the second combustion chamber. Accordingly, in such a gas generator, more significant effects can be obtained in changing the direction of the flame and the like of the ignition means by the porous tube member and in preventing the filter means from being eroded and the like.

[0036] Further, in the gas generator for the air bag according to the present invention in which the porous tube member is arranged, the gas generating agent (the first gas generating agent) stored in the combustion chamber (the first combustion chamber) formed outside the inner cylindrical member in the radial direction can be used without questioning the ignition performance thereof. In other words, the direction of the flame and the like of the ignition means for igniting the first gas generating agent is changed by the porous cylindrical member, even the gas generator having the insufficient ignition performance can be used.

[0037] The ignition performance of the gas generating agent can be, for example, judged by a period of time (T) from the time when the gas generating agent starts combustion to the time when the gas generator discharges the combustion gas. That is, in the gas generator not using the porous tube member of the present invention, in the case that the time T is not shorter than 8 milliseconds, or not shorter than 5 milliseconds, a gas generating agent can be regarded as the one having the insufficient ignition performance.

[0038] Then, in the gas generator according to the present invention, since the porous tube member is used, it is possible to use such a gas generator having the insufficient ignition performance. Accordingly, as the first gas generating agent, it is possible to use the agent which generates a combustion gas at 8 milliseconds or more after applying the activation signal to the igniter in the gas generator in which the porous tube member is not arranged. Naturally, even if such a gas generating agent is used in the gas generator according to the present invention, the ignition performance of the gas generating agent can be improved by the porous tube member and a period of time (T) from the time when the gas generating agent starts burning to the time when the gas generator discharges the combustion gas can be made not longer than 8 milliseconds, desirably than 5 milliseconds.

[0039] Accordingly, the effect of the present invention can be confirmed by that a period of time (T) from the time when the gas generating agent starts burning to the time when the gas generator discharges the combustion gas is changed from normally not shorter than 8 milliseconds to not longer than 8 milliseconds (desirably than 5 milliseconds) by providing the porous tube member in the housing.

[0040] The porous tube member used in the above-mentioned gas generator can be also used in the conventionally proposed gas generators, promising the effect mentioned above.

[0041] Further, the gas generator mentioned above can constitute an air bag apparatus together with an impact sensor detecting the impact to activate the gas generator, an air bag introducing therein a gas generated in the gas generator to inflate, and a module case for accommodating the air bag.

[0042] The gas generator is stored in the module case together with the air bag (the bag body) introducing therein the generated gas to inflate, thereby being provided as a pad module.

[0043] In the air bag apparatus, the gas generator is activated reacting upon the impact sensor detecting the impact to discharge a combustion gas from a gas discharge port in the housing. The combustion gas flows into the air bag, and consequently, the air bag breaks the module cover to inflate so that a cushion is formed to absorb the impact between a hard structure in the vehicle and the occupant.

[0044] In the gas generator for the air bag according to the present invention, by arranging the porous tube member having the above-mentioned structure inside the filter means, it is possible to effectively ignite the gas generating agent stored in the combustion chamber provided outside the inner cylindrical member which concentrically defines the interior of the cylindrical housing, thereby for example, improving an ignition performance of the gas generating agent.

[0045] Further, it is possible to effectively protect the filter means from the flame of the ignition means for burning the gas generating agent in the combustion chamber provided outside the inner cylindrical member.

[0046] Besides, the present invention provides a multistage gas generating device included in an air bag apparatus which comprises a gas generator for an air bag having plural combustion chambers, and ignition signal-outputting means to send an ignition signal to the respective igniters, wherein a connection error of the respective igniters and the ignition signal-outputting device is eliminated, and an air bag apparatus can actuate always with a desirable output.

[0047] The present invention provides a multistage air bag apparatus wherein, in a gas generating device which comprises a multistage type gas generator for an air bag including a plurality of igniters and in which actuation signals are outputted from ignition signal-outputting means to each of the igniters by a lead wire having the connector, the connector is provided with defining means, and, when the ignition signal-outputting means and the igniters are connected through the lead wires, the respective connections are specified as a unique combination.

[0048] That is, according to the present invention, there is provided a multistage type air bag apparatus comprising:

[0049] a multistage type air bag gas generator accommodating a plurality of electrical ignition type igniters in a housing thereof;

[0050] an ignition-signal outputting means provided with outputting portions for outputting an activation signal to the igniters due to the impact as many as the igniters; and

[0051] a plurality of lead wires having connectors,

[0052] wherein the igniters and the outputting portions are connected by the lead wires having the connectors, and the connectors have defining means which decide the unique connection between the respective igniters and the respective outputting portions, and the defining means is realized by-changing at least one of a shape, the number, a size, a color and a position of the connector or of the conductive portion existing in the connector.

[0053] According to the present invention, there is provided a connector for a multistage type air bag apparatus used for a plurality of lead wires connecting the outputting portions to a plurality of igniters, characterized by a defining means which specifies the unique connection between the respective outputting portions and the respective igniters.

[0054] The defining means may be formed on the connector provided on at least one end of the lead wire connecting the igniter and the outputting portion, or the defining means may be formed on a way-connector provided at least one on the lead wire which connects the igniter and the outputting portion.

[0055] The lead wire may be provided in the same numbers as the electrical ignition type igniter provided n the gas generator. The ignition timing of each of a plurality of the igniters is individually adjusted in accordance with environmental condition at the time of actuation of the air bag apparatus.

[0056] When the igniter includes a connecting portion for connecting the igniter to the connector, and the defining means may be formed on the connecting portion of each of the igniters and the connector which connects the lead wire extending from the outputting portion to each of the igniters. When the outputting portion includes a connecting portion to be connected to the connector, the defining means may be formed on the connecting portion of the outputting portions and the connector which connects the lead wire extending from the gas generator to the outputting portion. The way-connector may comprise a plug portion and a jack portion, these portions includes connecting portions, the defining means may be formed on the connecting portions of the plug portion and the jack portion of the way-connector which connects the lead wire extending from the gas generator and the lead wire extending from the outputting portion.

[0057] Conductive portions exist on the connector and the connecting portion, the respective conductive portions are brought into contact with each other by connecting the connector and the connecting portion so that ignition signal outputted from the ignition signal-outputting means can be transferred to each of the igniters. In this case, the defining means can be realized by changing at least one of a shape, a size, a color the number and a position of the conductive portion existing on the connector. And the defining means can be also realized by forming a position-deciding portion at a flange-portion formed in the housing.

[0058] For example, the conductive portion of the connector is of convex shape or concave shape, and is connected to the conductive portion of the connecting portion which is formed into a concave shape or convex shape. When the connector provided in each lead wire is made of plastic member, the plastic member may be provided with a defining means, and the connector and the connecting portion, or the a plurality of connectors can be connected to one another by the defining means. The plurality of lead wires are converged into one connector, and the connector can be provided with a defining means.

[0059] As described above, in the multistage air bag apparatus, if the connector having the defining means is used for the lead wire for connecting the ignition signal-outputting means and the igniter and for transmitting the actuation signal, it is possible to specify the unique connection of the respective igniters, the respective connectors and the respective actuation outputting means.

[0060] In this multistage type air bag apparatus, it is possible to use a gas generator having a cylindrical housing comprising a diffuser shell including a gas discharge port and a closure shell forming an internal space in cooperation with the diffuser shell. A plurality of igniters may be arranged in the same direction as the axis of the housing, and provided in the closure shell.

[0061] Further, according to the present invention, there is provided a multistage type gas generator comprising:

[0062] a plurality of igniters activated by an electric signal;

[0063] a gas generating means burning and/or expanding due to an activation of the igniters so as to generate an operating gas;

[0064] the igniters and the gas generating means being stored within a housing having a gas discharge port,

[0065] wherein each of the igniters has a connecting portion for joining a connector arranged at a tip end of a lead wire transmitting an activation signal outputted from an outputting portion of an ignition-signal outputting means, a defining means capable of connecting only one of the connectors of a plurality of lead wires extending from the outputting portion is provided in the connecting portion, the connectors and the igniters have conductive portions which enable the ignition-signal outputting means and the igniter to transfer to each other by connecting and contacting the connectors and the igniters, and the defining means can be realized by changing at least one of a shape, the number, a size, a color and a position of the connector or of the conductive portion existing in the connector, at the respective igniters, and/or by a positioning means provided in a flange formed on the housing.

[0066] This gas generator has, when the gas generator is assembled into the air bag apparatus, the connecting portion for connecting to connectors disposed on tip ends of lead wires which transmit an activation signal outputted from an ignition signal-outputting means, and the connecting portion is provided with a defining means which enables to connect only one of the connectors. As an example of the defining means, the conductive portions in the igniters, which receives the actuation signal from the ignition signal-outputting means, are different from each other in a shape, a size a color, the number and/or a position for the respective igniters. In other words, by making the conductive portions different from each other for the respective igniters at least one of a shape, a size a color, the number and a position, only the corresponding specific connector can be connected. Alternatively, the shape of the connecting portion of the igniter can be formed into a shape which is complementarily fitted only to the specific connector. In the latter case, a groove and/or a projection can be formed on the connecting portion so that positions and/or shapes thereof are different from each other at the respective igniters.

[0067] Further, a positioning means may be provided in a flange formed on the gas generator which is used at the time of mounting a module case. Consequently, the positions of the respective igniters become unique to be able to connect a corresponding connector exclusively.

[0068] This gas generator is good enough as long as it includes two or more igniters, and the gas generating means for generating the actuation gas for expanding the air bag (bag) may be solid gas generating agent or pressurized gas. And the gas generator may be formed into either shape suitable to be disposed on a driver side or suitable to be disposed on a passenger side. This gas generator preferably has a structure such that combustion chambers as many as igniters are provided in the housing, and gas generating means in each combustion chamber is burnt and expanded at each igniter.

[0069] Further, the present invention provides a connecting method for connecting the ignition signal outputting means (outputting portion) and the igniter, which is preferably used in the multistage type air bag apparatus mentioned above.

[0070] That is, there is provided a connector connecting method of connecting an ignition-signal outputting means which includes a control unit for sending an ignition signal to a plurality of igniters included in a gas generator, and a plurality of ignition means included in the gas generator, wherein each of the igniters is connected to an outputting portion of an ignition means outputting device through a lead wire having a connector, and connections of the respective igniters and the respective outputting portions are specified by defining means, the connectors and the igniters have conductive portions which enable the ignition-signal outputting means and the igniter to transfer to each other by connecting and contacting the connectors and the igniters, and the defining means can be realized by changing at least one of a shape, the number, a size, a color and a position of the connector or of the conductive portion existing in the connector, at the respective igniters, and/or by a positioning means provided in a flange formed on the housing

[0071] As for the defining means, the conductive portions provided on the respective igniters are formed differently from each other in at least one of a shape, a size, a color, the number and/or a position at the respective igniters. Alternatively, the defining means can be realized by forming the connector and the connecting portion so as to be fitted to each other complementarily, and thereby the combination thereof is unique. Especially, the latter case can be realized by forming a groove and/or a projection on the connecting portion which is different from each other in a position and/or a shape thereof at each igniter.

[0072] Usually, modules comprising the gas generator and the air bag (bag) are different in size and shape in accordance with a disposed position such as a driver side or a passenger side, but the multistage type air bag apparatus of the invention can be used irrespective of the shape and size of the module. Similarly, the gas generator for the multistage type air bag of the invention can be employed to any apparatus such as for a drive side, a passenger side and a backseat regardless of variation of shape and size.

[0073] In the multistage type air bag apparatus, any actuation signal outputting apparatus can be used as long as it includes a plurality of actuation signal outputting portions, the outputting timing of the actuation signal outputted from the outputting portions can be adjusted and it senses an impact and outputs the actuation signal. Therefore, the actuation signal outputting apparatus can be used as long as it includes a portion sensing the impact, and a portion for judging a degree of the impact and controlling the output signal, without regard to a structure whether the two portions are integrally formed or separately formed.

[0074] In the above-described multistage type air bag apparatus, for optimizing the developing pattern of the air bag (bag), when the actuation signal outputting means senses an impact, the outputting timing of the actuation signal is adjusted, and actuation timing of each igniter included in the gas generator is adjusted. At that time, since the connectors of the lead wires connecting the ignition signal-outputting means and the ignitions are provided with defining means respectively, the actuation signal outputted from the actuation signal outputting means is reliably sent to the specific igniter, i.e., the igniter which is initially planned to be actuated, no variation of actuation performance of the air bag apparatus is caused due to connection error of the ignition signal-outputting means and the igniter. Therefore, in this multistage type air bag apparatus, it is possible to optimize the developing pattern of the air bag more reliably.

[0075] Further, the present invention provides a positioning means which can be used not only in the multistage type gas generator mentioned above, but also in a gas generator provided at least one ignition means.

[0076] That is, there is provided a gas generator for an air bag comprising:

[0077] at least one igniter activated by the electric signal;

[0078] a gas generating means burning and/or expanding due to an activation of the igniter so as to generate an operating gas; and

[0079] the igniter and the gas generating means being stored in a housing having a gas discharge port,

[0080] wherein each of the igniters exposes a conductive portion, which receives the activation signal, out of the housing, and a defining means for specifying the unique connection between the respective conductive portions and the respective connectors of a plurality of the lead wires extending from the outputting portions is provided in a portion where the conductive portions are exposed.

[0081] For example, in the case that a ring member is interposed between the igniter and the connector at a time of connecting to the connector of the lead wire, the defining means can be formed in a portion where the ring member is arranged in the gas generator. Accordingly, the connection between the ring member and the igniter can be uniquely decided, thereby realizing the unique connection between the respective igniters and the connectors.

[0082] The ring member is arranged in the conductive portion (two conductive pins or the like) of the electrical ignition type igniter protruding out of the housing for receiving the ignition electric current, and can achieve a short-circuit between the conductive portions. That is, the conductive portion electrically connecting the conductive portions to each other so as to close a circuit may be included in the ring member. In this case, the gas generator (or the igniter) for the air bag to which the ring member is connected is not activated due to an unexpected external electric energy. Desirably, the conductive portion included in the ring member and electrically connecting the conductive portions of the igniter to each other is connected to the connector of the lead wire for transmitting the activation signal, thereby preventing the electrical connection between the conductive portion of the igniter such as the conductive pin or the like and the conductive portion of the ring member (that is, making them insulative) In this case, the circuit of the igniter is opened due to the connection with the connector, and the conductive portion is connected to the ignition signal outputting means via the lead wire or the like.

[0083] Further, the ring member preferably used in the gas generator mentioned above is also a feature of the present invention.

[0084] That is, there is provided a ring member of a gas generator for an air bag, arranged between an igniter of a gas generator for an air bag and a tip end of a lead wire transmitting an activation signal to the igniter, wherein a defining means for specifying the unique connection between the respective igniters and the respective connectors of the lead wires is provided in the ring members. The defining means can be formed to specify the unique connection between the respective ring members and the respective igniters and/or the unique connection between the respective ring members and the respective connectors of the lead wires.

[0085] Then, by using the above-mentioned gas generator and the ring member, there can be realized an air bag apparatus comprising:

[0086] a gas generator for an air bag storing at least one electrical ignition type igniter in a housing;

[0087] an ignition signal outputting means having outputting portions for outputting the activation signal to the igniter due to the impact as many as the igniters; and

[0088] lead wires having connectors as many as the electrical ignition type igniters,

[0089] wherein a defining means for specifying the unique connection between the respective igniters and the respective connectors of the lead wires is provided in the igniter.

[0090] In the case that a ring member interposed between the igniter and the connector of the lead wire at a time of connecting to the connector of the lead wire is arranged in the igniter, the defining means can be formed in the ring member. At this time, the defining means can be formed to specify the unique connection between the respective ring members and the igniters and/or the unique connection between the ring members and the connectors of the lead wires.

[0091] The present invention can realize a multistage gas generating device included in an air bag apparatus which comprises a gas generator for an air bag having plural combustion chambers, and ignition signal-outputting means to send an ignition signal to the respective igniters, wherein a connection error of the respective igniters and the ignition signal-outputting device is eliminated, and an air bag apparatus can actuate always with a desirable output. Therefore, in the multistage gas generating device which enables to control an actuating output and timing of increase of output arbitrarily, the efficacious actuation performance can be obtained constantly.

[0092] The present invention can be realized by combining at least two of the above mentioned structural requirements and functions.

[0093] And the gas generator of the present invention can be used in the above-mentioned multistage air bag apparatus.

BRIEF DESCRIPTION OF DRAWINGS

[0094]FIG. 1 is a vertical cross sectional view of a gas generator for an air bag according to the present invention;

[0095]FIG. 2 is a perspective view of a porous tube member in FIG. 1;

[0096]FIG. 3 is a vertical cross sectional schematic view showing an embodiment of an air bag apparatus according to the present invention;

[0097]FIG. 4 is a perspective schematic view showing other embodiment of the air bag apparatus;

[0098]FIG. 5 is a perspective schematic view showing an embodiment of a defining means;

[0099]FIG. 6 is a perspective schematic view showing other embodiment of the defining means;

[0100]FIG. 7 is a perspective schematic view showing still other embodiment of the air bag apparatus;

[0101]FIG. 8 is a perspective schematic view showing still other embodiment of the air bag apparatus;

[0102]FIG. 9 is a perspective schematic view showing still other embodiment of the defining means;

[0103]FIG. 10 is a perspective schematic view showing still other embodiment of the air bag apparatus;

[0104]FIG. 11 is a vertical cross sectional schematic view showing an embodiment of a gas generator according to the present invention;

[0105]FIG. 12 is a perspective schematic view showing still other embodiment of the air bag apparatus; and

[0106]FIG. 13 is a vertical cross sectional schematic view showing other embodiment of the gas generator according to the present invention.

DESCRIPTION OF REFERENCE NUMERALS

[0107]210 ignition means

[0108]223 igniter

[0109]231 collar assembly

[0110]250 tube portion

[0111]251 flame-preventing annular portion

[0112]252 porous annular portion

[0113]253 opening

[0114]260 flame-like portion

[0115]270 porous tube portion

[0116]100 gas generator for an air bag

[0117]101 diffuser shell

[0118]102 closure shell

[0119]103 housing

[0120]104 inner-cylindrical chamber

[0121]105 combustion chamber

[0122]107 partition wall

[0123]108 seal-up member

[0124]109 gas generating agent

[0125]110 through-hole

[0126]112 ignition means accommodating chamber

[0127]116 transfer charge

[0128]117, 119 flame-transferring hole

[0129]122 coolant/filter

[0130]124 outer layer

[0131]125 gap

[0132]126 gas discharge port

[0133]1 gas generator for an air bag

[0134]2 activation signal-outputting means

[0135]3 air bag

[0136]7 activation signal-outputting portion

[0137]8 igniter

[0138]9 lead wire

[0139]10 connector

[0140]42 ring member

[0141] Preferred Embodiment of the Invention

[0142] A description will be given of an embodiment of a gas generator for an air bag according to the present invention with reference to FIGS. 1 and 2. FIG. 1 is a vertical cross sectional view of a gas generator for an air bag according to the present invention and FIG. 2 is a perspective view showing a porous tube member in FIG. 1.

[0143] A gas generator 100 shown in FIG. 1 is structured such that an inner cylindrical member 104 formed in a substantially cylindrical shape is arranged inside a housing 103 obtained by joining a diffuser shell 101 having a gas discharge port and a closure shell 102 forming an inner accommodating space together with the diffuser shell 101 and a first combustion chamber 105 a is provided in the outside thereof. Further, a stepped notch portion 106 is provided inside the inner cylindrical member 104, a partition wall 107 formed in a substantially disk-like shape is arranged in the stepped notch portion 106, and the interior of the inner cylindrical member 104 is divided into two chambers by the partition wall 107 and a seal cup member 108 engaging therewith. The interior of the inner cylindrical member 104 is divided into a second combustion chamber 105 b in the diffuser shell side and an ignition means accommodating chamber 112 in the closure shell side. Consequently, in this gas generator, the first combustion chamber 105 a and the second combustion chamber 105 b are concentrically provided inside the housing 103 and arranged adjacent in the radial direction of the housing 103.

[0144] A first gas generating agent 109 a and a second gas generating agent 109 b which is to be burned by an ignition means 210 activated upon the impact to generate a combustion gas are stored within the first and second combustion chambers respectively. Reference numeral 150 in the second combustion chamber 105 b denotes an automatic igniting material. This automatic igniting material is ignited and burned due to a heat transmitted through a housing or the like.

[0145] The first and second gas generating agents 109 a and 109 b can be gas generating agents having different shapes from each other (for example, a gas generating agents having a single hole a gas generating agent with a multiple holes) respectively at first and second combustion chambers 105 a and 105 b. Further, an amount of the gas generating agent stored in each of the combustion chambers 105 a and 105 b can be suitably adjusted. Naturally, a shape, a composition, a composition ratio, an amount and the like of the gas generating agent can be changed suitably for obtaining a desired output performance. Particularly, in the gas generator shown in the present embodiment, the first gas generating agent 109 a stored in the first combustion chamber 105 a comprises a fuel and an oxidizer, and a gas generating agent comprising a basic copper nitrate as the oxidizer and, in particular, a guanidine derivative or a mixture thereof as the fuel is used.

[0146] An ignition means 210 including two igniters 223 and a transfer charge 116 charged in an aluminum cup is stored in an ignition means accommodating chamber 112 defined in the closure shell side inside the inner cylindrical member 104. Two igniters 223 a and 223 b are fixed to a collar assembly 231 and fitted into the inner cylindrical member 104 (into a space formed by the inner cylindrical member 104 and the partition wall 107), and this is mounted by crimping a lower end portion 104 a of the inner cylindrical member 104 so as to fix the collar assembly 231. The first igniter 223 a and the second igniter 223 b are respectively stored in a space defined by a seal cup member 108 constituting the partition wall 107, and the transfer charge 116 is arranged above the first igniter in the space where the first igniter 223 a is stored.

[0147] The space in which the first igniter 223 a and the transfer charge 116 are stored can communicate with the first combustion chamber 105 a formed outside the inner cylindrical member 104 in the radial direction by a flame-transferring hole 117 provided in the inner cylindrical member, and the space in which the second igniter 223 b is stored can communicate with the second combustion chamber 105 b by a flame-transferring hole 119 on the partition wall 107. Accordingly, when the first igniter 223 a is activated, the transfer charge 116 existing right above is ignited and burnt, and a flame and a heat thereof are ejected into the first combustion chamber 105 a through the flame-transferring hole 117 formed in the inner cylindrical member 104 to ignite and burn the first gas generating agent 109 a. Meanwhile, when the second igniter 223 b is activated, a flame is ejected into the second combustion chamber 105 b through the flame-transferring hole 119 on the partition wall to ignite and burn the second gas generating agent 109 b. The combustion gas generated due to the combustion of the second gas generating agent passes through a through-hole 110 formed in the inner cylindrical member 104 and is ejected into the first combustion chamber 105 a. The through-hole is closed by a seal tape 111, however, the seal tape 111 is ruptured due to the combustion of the gas generating agent, whereby both combustion chambers 105 a and 105 b communicate with each other. In this seal tape 111, a material and a thickness thereof has to be adjusted so that the seal tape is not ruptured due to the combustion of the first gas generating agent 109 a in the first combustion chamber 105 a but is ruptured due to the combustion of the second gas generating agent 109 b in the second combustion chamber 105 b. In the present embodiment, a stainless seal tape having a thickness of 40 μm is employed. Further, the through-hole 110 has an opening area larger than that of the gas discharge port 126, and does not have a function of controlling the internal pressure in the combustion chamber 105 b.

[0148] Further, a common coolant/filter 122 for cooling and/or purifying the combustion gas generated due to the combustion of the first and second gas generating agents 109 a and 109 b is arranged in the housing 103 as a filter means. The coolant/filter 122 can employ a structure formed by winding a metal wire mesh to be laminated or a structure formed by winding an expanded metal to be multiple-layered.

[0149] Further, a porous tube member 270 having a plurality of openings is arranged inside the coolant/filter 122. The porous tube member 270 comprises, as shown in FIG. 2, a tube portion 250 facing an inner circumferential surface of the coolant/filter 122 and an inwardly shaped portion 260 like a flange which is integrally formed in one end opening of the tube portion in an inward flange shape. And the tube portion 250 is constituted by a flame-preventing annular portion 251 having no opening and a porous annular portion 252 having a plurality of openings 253, and both annular portions 251 and 252 are provided adjacent to each other in the axial direction of the tube portion 250.

[0150] In the porous cylindrical member 270, a portion crossing the ejecting direction of the flame and/or the heat of the ignition means (that is, the transfer charge ignited and burned by the activation of the first igniter 223 a) ejected out from the flame-transferring hole is formed as the flame-preventing annular portion 251 having no opening, and a portion crossing the ejecting direction of the combustion gas ejected out from the through-hole 110 which is generated due to the combustion of the second gas generating agent 109 b, is formed as the porous annular portion 252 having a plurality of openings 253.

[0151] A plurality of flame-transferring holes 117 and a plurality of through-holes 110 are respectively arranged on the periphery of the inner cylindrical member parallelly in a circumferential direction thereof, the flame-preventing annular portion 251 of the porous tube member 270 is arranged so as to face the flame-transferring holes 117 and the porous annular portion 252 is arranged so as to face the through-hole 110.

[0152] Accordingly, even when the flame and the heat generated due to the combustion of the transfer charge 116 are ejected into the first combustion chamber 105 a through the flame-transferring holes 117 formed in the inner cylindrical member 104, the direction of the flame or the like is changed by the flame-preventing annular portion 251 of the porous tube member 270 so that the flame can be spread the entire interior of the first combustion chamber 105, in particular, the flame can reach the gas generating agent 109 a stored in the diffuser shell 101 side. In other words, it is possible to avoid the situation such that the flame, the heat and the like generated due to the combustion of the transfer charge 116 directly passes through the first combustion chamber 105 a and the coolant/filter 122. Accordingly, the first gas generating agent 109 a is effectively and unfailingly ignited, and an ignition performance thereof can be improved. In addition, by the flame-preventing annular portion 251, the coolant/filter 122 can be protected from the flame and the like ejected from the flame-transferring hole 117, and thereby erosion thereof can be avoided.

[0153] The gas generated due to the combustion of the second gas generating agent 109 b stored in the second combustion chamber 105 b ejects into the first combustion chamber through the through-hole 110 of the inner cylindrical member 104. Then, the gas reaches the coolant/filter 122 to be cooled and purified after directly passing through the porous annular portion 252 of the porous tube member 270.

[0154] Particularly, in the porous tube member 270 shown in the present embodiment, the inwardly shaped portion like a flange is integrally formed at one end opening of the tube portion facing the inner circumferential surface of the coolant/filter 122, and thereby the porous tube member can be securely arranged in the housing. Further, an opening 253 is not formed in the edge, flanging, of the tube portion 250, which can prevent the combustion gas from passing through the end surface of the coolant/filter 122.

[0155] In this case, in this gas generator housing 103, gas discharge ports 126 are distributed in the diffuser shell 101 side on the periphery of the tube portion of the housing, and the flame-transferring holes 117 formed in the inner tube member 104 and the flame-preventing annular portion 251 of the porous tube member 270 are arranged in the closure shell 102 side where gas discharge ports of the cylindrical housing are not formed. Further, the flange portion 260 of the porous tube member 270 is arranged in contact with an inner surface of the ceiling portion of the diffuser shell 101 where gas discharge ports are provided.

[0156] The outer side of the coolant/filter 122 is supported by an outer layer 124 so that the coolant/filter is prevented from expanding when the combustion gas passes or the like. A gap 125 is formed in the outer side of the outer layer 124 so that the combustion gas can pass through the entire portion of the coolant/filter 122. The gas discharge port 126 formed in the diffuser shell is closed by a seal tape 127 so as to prevent the ambient air from entering. The seal tape 127 is ruptured when the gas is discharged. The seal tape 127 is provided in order to protect the gas generating agent from a moisture in the ambient air, and does not affect any adjustment of performance such as a combustion internal pressure or the like.

[0157] Next, a description will be given of an activation of the gas generator 100 for the air bag shown in FIG. 1. When the transfer charge 116 is ignited and burned by the activation of the first igniter 223 a, a flame thereof ruptures the seal tape 118 closing the flame-transferring hole 117 formed in the inner cylindrical member 104, enters the first combustion chamber 105 a, and ignites and burns the first gas generating agent 109 a to generate a gas.

[0158] When the second igniter 223 b is activated at the same time of or slightly after the activation of the first igniter 223 a, a flame generated by the activation ruptures the seal tape 120 closing the flame-transferring hole 119 formed in the partition wall 107, enters the second combustion chamber 105 b, and ignites and burns the second gas generating agent 109 b to generate a gas. The combustion gas generated within the second combustion chamber 105 b passes through the through-hole 110 provided in the diffuser shell 101 side of the inner cylindrical member 104 and flows into the first combustion chamber 105 a.

[0159] As described above, it is possible to optionally adjust the output performance (the activation performance) of the gas generator 100 by adjusting the ignition timing of the first and second igniters 223 a and 223 b, that is, by activating the second igniter 223 b after activating the first igniter 223 a or activating the first and second igniters 223 a and 223 b simultaneously, so that under various conditions such as a vehicle speed at a time of collision, an environmental temperature and the like, an development of the air bag in the air bag apparatus mentioned below can be made most proper.

[0160] The gas generator shown in FIG. 1 includes at least two combustion chambers for storing the gas generating agent. However, since the gas generator for the air bag according to the present invention is characterized by improving ignition of the gas generating agent stored in the combustion chamber provided outside in the radial direction of the inner cylindrical member concentrically defining the interior of the housing, the structure of the gas generator for the air bag is not particularly limited, for example, only one a gas generating agent may be provided in the housing.

[0161] In this case, the porous tube member of the gas generator for the air bag according to the present invention can be easily realize by referring to the embodiment mentioned above and FIG. 2.

[0162] Further, an air bag system according to the present invention using the gas generator for the air bag mentioned above is provided with an activation signal outputting means comprising an impact sensor and a control unit, and a module case in which the gas generator 100 and the air bag are stored. The gas generator 100 for the air bag is connected to the activation signal outputting means (the impact sensor and the control unit) in the first and second igniters 223 a and 223 b side. Further, in the air bag system having the structure mentioned above, by suitably setting an activation signal outputting condition in the activation signal outputting means, it is possible to adjust gas generating amount and an inflating speed of the air bag corresponding to a degree of the impact.

[0163] Multistage Air Bag Apparatus

[0164] The multistage gas generator for an air bag apparatus of the present invention will be explained based on the embodiment shown in the drawing below. FIG. 3 is a vertical cross sectional view showing one embodiment of the multistage type air bag apparatus of the invention.

[0165] The multistage type air bag apparatus shown in this drawing comprises a gas generator 1 for a multistage type air bag including two igniters 8 a and 8 b, and an actuation signal outputting means 2 for outputting actuation signal to each igniter in accordance with an impact. Among them, the gas generator 1 for the multistage type air bag is accommodated in a module case 4 together with an air bag 3 which is to be expanded by introducing an actuation gas generated by actuation of the gas generator.

[0166] The actuation signal outputting means 2 comprises an impact sensor 5 which senses an impact and a control unit 6 for inputting a signal from the impact sensor and outputting the ignition actuation signal.

[0167] The impact sensor 5 is for sensing the impact, and can be formed using a semiconductor acceleration sensor for example. In the semiconductor acceleration sensor, four semiconductor strain gauges are formed on a beam of a silicon substrate which deflects if acceleration is applied, and the semiconductor strain gauges are bridge-connected. When acceleration is applied, the beam is bent, and strain is generated on the surface. With this strain, resistance of the semiconductor strain gauge is changed, and the resistance change is detected as a voltage signal in proportion with the acceleration.

[0168] The control unit 6 includes an ignition judging circuit. A signal from the semiconductor strain gauges is inputted to the ignition judging circuit. When an impact signal from the sensor 5 exceeds a certain value, the control unit 6 starts calculation, and when the calculated result exceeds a certain value, an actuation signal is outputted to the igniters 8 a and 8 b of the gas generator 1.

[0169] The module case 4 is made of polyurethane, for example, and includes a module cover 29. The air bag 3 and the gas generator 1 are accommodated in the module case 4 to constitute a pad module. When the pad module is mounted to the driver side of an automobile, it is usually mounted in a steering wheel 30.

[0170] The air bag 3 is made of nylon (e.g., nylon 66) or polyester and the like, its bag port 31 surrounds a gas discharge port of the gas generator, and the air bag is fixed to the flange portion of the gas generator in a folded state.

[0171] In the multistage type air bag apparatus having the above-described structure, when the semiconductor acceleration sensor 5 senses an impact at the time of collision of the automobile, its signal is sent to the control unit 6, and when the impact signal from the sensor exceeds the certain value, the control unit 6 starts calculation. If the calculated result exceeds the certain value, the actuation timing is adjusted, and the actuation signal is outputted to the igniters 8 a and 8 b. With this, the igniters 8 a and 8 b are actuated to ignite and burn the gas generating agents for generating a combustion gas. The gas is ejected into the air bag 3, and the air bag breaks the module cover 29 and expands, and then forms a cushion between the steering wheel 30 and the passenger for absorbing the impact.

[0172] The actuation signal outputted from the control unit 6 is outputted from an outputting portion 7 provided in the respective igniters 8 a and 8 b in the control unit 6. The number of the outputting portions 7 should be more than the number of igniters 8 included in the gas generator 1, i.e., two or more in the present embodiment. For adjusting the actuation timing of the igniters, the actuation signals from the outputting portions 7 a and 7 b can be outputted at different timings. The actuation signals outputted from the outputting portions 7 a and 7 b transmitted to the igniters 8 a and 8 b included in the gas generator 1 by the lead wires 9 a and 9 b provided in the same numbers as the igniters 8 a and 8 b. In this case, if wrong lead wire 9 is erroneously connected to any of the igniter, desired actuation output can not be obtained. Thereupon, the lead wires 9 a and 9 b for connecting the outputting portions 7 a, 7 b and the igniters 8 a and 8 b are provided with connectors 10 a and lob, and connectors 10 a and 10 b are provided with defining means. With this arrangement, actuation signal outputted from the first outputting portion 7 a is reliably sent to the first igniter 8 a, and actuation signal outputted from the second outputting portion 7 b is reliably sent to the second igniter 8 b. The defining means can be formed differently in accordance with a structure of the igniter 8 and the control unit 6 or a shape of the lead wire 9 for connecting the igniter 8 and the outputting portion 7.

[0173] In the multistage type air bag apparatus of FIG. 3, as shown in FIG. 4, when the connectors 10 a and 10 b are mounted to tip ends of the lead wires 9 a and 9 b respectively extending from the outputting portions 7 a and 7 b, and the respective connectors 10 a and 10 b are connected to connecting portions 11 a and 11 b of the igniter 8 a and 8 b, connectors 10 a and 10 b and the connecting portions 11 a and 11 b can be provided with defining means as shown in FIGS. 5 and 6. When the connector 10 of the lead wire 9 is connected to the igniter in this manner, a conductive portion i.e., a conductive pin 12, which receives the actuation output from the control unit 6, is used.

[0174] In the defining means shown in FIG. 5, shapes of the connecting portion are different from each other at the respective igniters, or a groove and/or a projection are formed so that positions and/or shapes thereof are different from each other at the respective igniters. In the case of the defining means shown in FIG. 5a, positioning grooves (or projections) 17 are formed on the connectors 10 a and 10 b, and positions where projections (or grooves) 18 corresponding to the positioning grooves (or projections) 17 are different from each other at each igniter. In the case of the defining means shown in this drawing, positions of the grooves (or projections) 17 of the connectors are different from each other so that, at the time of mounting the connectors 10 a and 10 b to the gas generator, if the connectors are not mounted in the right direction, the connectors interfere with each other and they can not be mounted right. In the defining means shown in FIG. 5b, only one connector 10 b is provided with a positioning groove (or projection) 19. That is, a connector 10 b having the groove (or projection) 19 can be connected to an igniter 8 a which does not have a projection (or groove) 20, but a connector 10 a which does not have the grove (or projection) 19 can not be connected to an igniter 8 b having the projection (or groove) 20. As a result, connection error of the connectors can easily be found at the time of assembling. In FIG. 5c, the shapes of connecting portions 16 of the connectors 10 a and 10 b are different from each other. In FIG. 5d, two connectors are formed into one connector, and a positioning groove (or projection) 24 is formed.

[0175] As the gas generator shown in FIG. 4, when the conductive pin 12 is provided as the conductive portion on the connecting portion to which the connector is connected and the conductive portion (the conductive pin 12) of the connecting portion 11 is connected to the conductive portion of the connector 10 so that current can flow, the shape, the number or the position of the conductive pin 12 can be changed in each igniter, and in accordance with this, the shape, the number or the position of the conductive portion of the connector 10 can be changed.

[0176]FIG. 6 shows a mode of the conductive pins different from each other at the respective igniters. FIG. 6a shows that the shapes of the conductive pins 12 of the igniters 8 a and 8 b are different, and FIG. 6b shows that the conductive pins 12 of the igniters 8 a and 8 b are formed at the different positions. Such mode of conductive pins can be appropriately employed as long as the respective igniters have different conductive pins form each other. In this case, the shape, the position or the number of the conductive portions of the connectors 10 a and 10 b in FIG. 4 are adjusted in accordance with a mode of the conductive pins 12 of the igniters 8 a and 8 b. When the conductive pins 12 of the igniters 8 a and 8 b are formed at the different positions as shown in FIG. 6b, the connectors 10 a and 10 b can also be connected as shown in FIG. 6c.

[0177] When the defining means are provided to connect the igniters and the connectors 10 a and 10 b as described above, the connectors 10 a and 10 b are preferably designed so that the lead wires 9 a and 9 b which are connected to the respective connectors 10 a and 10 b are pulled out in the same direction and further, that direction is perpendicular to the center axis of the housing.

[0178] In the other aspects, although an illustration is omitted, the connecting portions 11 a and 11 b of the igniters 8 a and 8 b and the respective connectors 10 a and 10 b connected thereto may be set to have the same color. In other words, the respective connectors 10 and the respective connecting portions 11 are colored so that a red connector 10 a is connected to a red connecting portion 11 a and a yellow connector 10 b is connected to a red connecting portion 11 b.

[0179] Further, in the case that a ring members 42 are interposed between the igniters 8 a and 8 b and the connectors 10 a and lob connected thereto respectively, as shown in FIG. 12, a positioning member may be provided in the ring member 42. Generally, the ring member 42 is arranged in each of the igniters for the purpose of electrically connecting the conductive pins 12 with each other so as to intentionally achieve a short-circuit, and is arranged in each of the connecting portions 11 a and 11 b. It is necessary that a defining means formed in the ring members 42 a and 42 b specifies the unique connection between each of the ring members 42 a and 42 b and each of the igniters 8 a and 8 b and/or the unique connection between each of the ring members 42 a and 42 b and each of the connectors 10 a and 10 b of the lead wires. The defining means in the connection between the ring member and the igniter and the defining means in the connection between the ring member and the connector of the lead wire joined with the inner side thereof can be achieved by the same way as that in the connection between each of the connecting portions 11 a and 11 b in each of the igniters and each of the connectors 10 a and 10 b.

[0180] Further, in the multistage type air bag apparatus shown in FIG. 3, when the ends of the lead wires 9 a and 9 b are provided with connectors 13 a and 13 b, and the connectors 13 a and 13 b are respectively connected to connecting portions 14 a and 14 b of the outputting portions 7 a and 7 b as shown in FIG. 7, the connectors 13 a and 13 b and the connecting portions 14 a and 14 b can be respectively provided with defining means similar to those of the igniters shown in FIG. 5. Namely, shapes of the connecting portions 14 a and 14 b of the outputting portions 7 a and 7 b are different at the respective connectors 13 a and 13 b, or grooves and/or projections which are different in position and/or shape are formed. In accordance with the connecting portions 14 a and 14 b of the outputting portions 7 a and 7 b, in this case, the connectors 13 a and 13 b are formed in shape to have positions and/or into shapes of the grooves and/or the projections respectively. Further, when the connecting portions 14 a and 14 b of the outputting portions 7 a and 7 b have conductive pins 15 a and 15 b which functions as the conductive portions, the conductive pins 15 a and 15 b can be formed into the mode shown in FIG. 6. In this manner, in the case of the multistage type air bag apparatus in which the connector 13 of the lead wire 9 is connected to the ignition signal-outputting means (the control unit 6 in the present embodiment), by providing the connecting portions 14 a and 14 b of the outputting portions 7 a and 7 b and the connectors 13 a and 13 b with the defining means, the lead wire 9 a is connected to the first outputting portion 7 a through the connector 13 a, and the lead wire 9 b is connected to the second outputting portion 7 b through the connector 113 b. Therefore, when the igniters 108 a and 8 b are connected to the lead wires 9 a and 9 b respectively, by providing the defining means shown in FIGS. 5 and 6, the actuation signal outputted from the first outputting portion 7 a is inputted to the first igniter 8 a without mistake, and the actuation signal outputted from the second outputting portion 7 b is inputted to the second igniter 8 b without mistake. With this arrangement, in the multistage type air bag apparatus, a desired actuation performance can be obtained reliably.

[0181] Further, in the multistage type air bag apparatus shown in FIG. 3, as shown in FIG. 8, when way-connectors 25 a and 25 b are connected to the intermediate portions of the lead wires which connect the outputting portions 7 a and 7 b of the ignition signal-outputting means (the control unit 6 in the present embodiment) and the gas generator for the multistage type air bag (the igniter 8 in the present embodiment), the way-connectors 25 a and 25 b can also be provided with defining means. That is, the defining means as explained in FIGS. 5 and 6 are provided in a plug 25 a 1 and a jack 25 a 2 of the way-connector 25 a, and in a plug 25 b 1 and a jack 25 b 2 of the way-connector 25 b. Such defining means can be realized by adjusting the shape of the connector itself or by providing or not providing concave and convex, or adjusting the position, shape and the like of the conductive pin so that the plug 25 a 1 can be connected only to the jack 25 a 2, and the plug 25 b 1 can be connected only to the jack 25 b 2. More specifically, as shown in FIG. 9(a) the locations where the conductive pins 21 of the plugs 25 a 1 and 25 b 1 can be set different from each other at the respective way-connectors 25 a and 25 b. Alternatively, as shown in FIG. 9(b), shapes of the conductive pins 21 of the plugs 25 a 1 and 25 b 1 can be made different from each other at the respective way-connectors 25 a and 25 b. Or as shown in FIG. 9(c), the shapes of the connectors 25 a and 25 b can be made different from each other. For example, as shown in FIG. 10, the method of providing the defining means to such way-connectors can be employed also when the igniters 26 a and 26 b provided in the gas generator do not directly connect the connectors. In other words, when the igniters include a connecting portion for connecting the connector, the defining means can be provided by the method as shown in FIGS. 5 and 6, but when the lead wires 27 a and 27 b are connected directly to the igniters 26 a and 26 b as shown in FIG. 10, it is difficult to connect the connectors directly to the igniters 26 a and 26 b. Thereupon, the lead wires 27 a and 27 b extending from the igniters 26 a and 26 b are provided at their tip ends with the connectors 28 a and 28 b, and the way-connectors 25 a and 25 b are connected to the connectors. If the connectors are respectively provided with the defining means and the way-connector 25 a is connected to the connector 28 a and the way-connector 25 b is connected to the connector 28 b, the actuation signal sent from the first lead wire 26 a is reliably transmitted to the first igniter 26 a, and the actuation signal sent from the second lead wire 26 b is reliably transmitted to the second igniter 26 b.

[0182] By the above-described structure and method, in this multistage type air bag apparatus, connection error of the outputting portion and the ignition is eliminated, and the actuation signals of the igniters outputted from the outputting portions 7 a and 7 b of the control unit 6 in the ignition signal-outputting means can be transmitted to the desired igniters. Therefore, according to this multistage type air bag apparatus, a desired actuation performance can reliably be obtained.

[0183] Multistage Gas Generator for an Air Bag

[0184]FIG. 11 is a vertical cross sectional view showing an embodiment of a multistage type air bag apparatus preferably used for the above-described multistage type air bag apparatus. Namely in this gas generator, the multistage type air bag is provided with defining means which can specify the connectors 10 a and 10 b mounted to tip ends of the lead wires connected to the ignition signal-outputting means and can connect the connectors, as explained in the above.

[0185] In this gas generator, two combustion chamber 32 a, b for accommodating gas generating agents are provided in a housing 32, and two igniters 35 a, b for burning gas generating agents 34 a, b disposed in the respective combustion chambers are accommodated. The igniters disposed in the housing can be actuated independently, and when one of the igniters is actuated, the gas generating agent in one of the combustion chambers is ignited and burnt. That is, this gas generator is adapted such that the gas generating agents 34 a, b in the combustion chambers 33 a, b are ignited and burnt only by either one of the igniters 35. Therefore, if the actuation timings of the igniters 35 a, b are adjusted, the burning timings of the gas generating agents 34 a, b in the combustion chambers can be adjusted, and with this feature, the actuation performance of the gas generator and the air bag apparatus can be adjusted. More specifically, when the first igniter 35 a is actuated, the transfer charge 36 is burnt, the flame is ejected from first flame-transferring hole 50 into the first combustion chamber 33 a to ignite and burn the first gas generating agent 34 a accommodated in the first combustion chamber. The second igniter 35 b is actuated simultaneously with or slightly later than the first igniter, and the flame passes through the second flame-transferring hole 50 b and ejected into the second combustion chamber. The second gas generating agent is ignited and burnt by this flame to generate the actuation gas, and the gas passes through the through-hole 52 of the inner cylindrical member 51 and is ejected into the first combustion chamber 33 a. The actuation gas generated by combustion of the first gas generating agent 34 a and the second gas generating agent 34 b is purified and cooled while the gas passes through the coolant/filter 37 and discharged from the gas discharge port 53.

[0186] In this gas generator, the transfer charge 36 capable of being ignited and burnt by the actuation of the igniter 35 to efficiently burn the gas generating agent can be combined in the igniter 35. When the gas generating agent 34 is burnt and combustion residue is also generated, a filter for purifying the combustion residue can be disposed, and a coolant for cooling the combustion gas can be disposed. In the present embodiment, the coolant/filter 37 for purifying and cooling the combustion gas is used.

[0187] In this gas generator, the two igniters are respectively accommodated in igniter collars 38 and disposed in the housing 32. In the igniter collar, the position where the igniter 35 is accommodated is provided with a connecting portion 39. Connectors 10 of tip ends of the lead wires 9 extending from the ignition signal-outputting means are respectively connected to the connecting portions when the air bag apparatus is formed using the gas generator.

[0188] In the gas generator of the present invention, the connecting portion 39 is provided with a defining means 40 so that among the plurality of connectors 10 a, b for transmitting the actuation signals from the ignition signal-outputting means to the igniters 35 a, b, the connector 10 a capable of being connected to the connecting portion 40 can be specified. That is, the defining means 40 of the igniter 10 a, b are formed differently at the respective igniters 10 a, b. For example, as shown in FIG. 5, the shapes of the connecting portions 39 a, b of the igniters 25 a, b can be formed differently from each other, or grooves and/or projections having different positions and/or shapes can be formed. Further, as shown in FIG. 6, shapes, positions or the like of the conductive pins 41 of the igniters projecting into the connections 39 a, b can be set different from each other at the respective igniters 35 a, b.

[0189] Although the gas generator suitable to be disposed on a driver side has been described in the present embodiment, a gas generator which is long in the axial direction suitable to be disposed on a passenger side, or a gas generator using pressurized gas instead of solid gas generating agent can be used as long as the gas generator includes two or more igniters.

[0190] The two igniters may not be always disposed on the same plane as shown in FIG. 11, and the igniters can also be disposed on different planes, e.g., on the upper surface and the lower surface of the gas generator.

[0191] Further, as shown in FIG. 13, ring members 42 a and 42 b formed in a substantially annular shape are inwardly fitted to connecting portions 39 a and 39 b provided in a portion in which the igniter 35 is stored, and in the case that the connector 10 at the tip end of the lead wire 9 is joined within center spaces of the ring members 42 a and 42 b, a defining means 40 corresponding to the joined ring members 42 a and 42 b can be provided in each of the connecting portions 39 a and 39 b. Accordingly, only the ring members 42 a and 42 b having the defining means corresponding to the igniters 35 a and 35 b are connected to the respective igniters 35 a and 35 b. 

1. A gas generator for an air bag in which an inner cylindrical member is arranged in a cylindrical housing having a gas discharge port to define the interior of the housing, an ignition means including an igniter activated by the activation signal and generating flame and/or heat due to an activation of the igniter is arranged inside the inner cylindrical member, a combustion chamber storing a gas generating agent ignited and burned by the flame and/or the heat generated by the ignition means to generate a combustion gas is provided outside the inner cylindrical member in the radial direction, and a cylindrical filter means for cooling and/or purifying the combustion gas is arranged outside the combustion chamber in the radial direction, wherein the ignition means is stored in an ignition means accommodating chamber defined in the inner cylindrical member, a flame-transferring hole for ejecting the flame and/or the heat, which are generated in the ignition means accommodating chamber due to the activation of the ignition means, into the combustion chamber is formed in the inner cylindrical member, a porous tube member having a plurality of openings is arranged inside the filter means in the radial direction, and in the porous tube member, at least a portion which crosses the ejecting direction of the flame and/or the heat of the ignition means ejected through the flame-transferring hole is formed as a flame-preventing annular portion having no opening.
 2. A gas generator for an air bag according to claim 1, wherein a second combustion chamber adjacent to the ignition means accommodating chamber in the axial direction, separated from the ignition means accommodating chamber by a partition wall and storing a second gas generating agent is provided in the inner cylindrical member and a combustion gas generated due to combustion of the second gas generating agent flows into the combustion chamber (a first combustion chamber) provided outside the inner cylindrical member in the radial direction through a through-hole formed on a circumferential wall of the inner cylindrical member.
 3. A gas generator for an air bag according to claim 2, wherein, in the porous tube member, at least a portion which crosses the ejecting direction of a combustion gas generated due to the combustion of the second gas generating agent ejected from the through-hole is formed as a porous annular portion in which a plurality of openings are provided.
 4. A gas generator for an air bag according to claim 2 or 3, wherein the plurality of flame-transferring holes and a plurality of through-holes are respectively arranged parallelly in a circumferential direction in the circumferential wall of the cylindrical member, the flame-transferring holes face the flame-preventing annular portion, and the through-holes face the porous annular portion
 5. A gas generator for an air bag according to any one of claims 1 to 4, wherein the porous tube member includes a tube portion comprising a flame-preventing annular portion having no opening and a porous annular portion having a plurality of opening, and the flame-preventing annular portion and the porous annular portion are provided adjacent to each other in the axial direction of the tube portion.
 6. A gas generator for an air bag according to any one of claims 1 to 5, wherein gas discharge ports provided in the cylindrical housing are distributed on either side in the axial direction of the circumferential surface of the cylindrical housing, and the flame-transferring hole and the flame-preventing annular portion exist in the side where gas discharge ports of the cylindrical housing are not formed.
 7. A gas generator for an air bag according to any one of claims 1 to 6, wherein the porous tube member comprises a tube portion facing an inner peripheral surface of the filter means and a flange portion which formed integrally with one end opening of the tube portion to have an inward shape like a flange.
 8. A gas generator for an air bag according to claim 7, wherein gas discharge ports provided in the cylindrical housing is distributed on either side in the axial direction of a circumferential surface of the cylindrical housing, and the flange portion contacts with an inner surface of a ceiling portion of the housing closing an axial end surface in the side where gas discharge ports are provided.
 9. A gas generator for an air bag according to any one of claims 1 to 8, wherein the gas generating agent (the first gas generating agent) stored in the combustion chamber (the first combustion chamber) formed outside the inner cylindrical member in the radial direction generates a combustion gas at 8 milliseconds or more after applying the activation signal to the igniter, in the gas generator provided with no the porous tube member.
 10. A gas generator for an air bag according to any one of claims 1 to 8, wherein the gas generating agent (the first gas generating agent) stored in the combustion chamber (the first combustion chamber) formed outside the inner cylindrical member in the radial direction generates a combustion gas within 8 milliseconds after applying the activation signal to the igniter, in the gas generator provided with the porous tube member.
 11. A gas generator for an air bag according to any one of claims 1 to 10, wherein the gas generating agent (a first gas generating agent) stored in the combustion chamber (the first combustion chamber) formed outside the inner cylindrical member in the radial direction comprising a fuel and an oxidizer, and the oxidizer is a basic copper nitrate.
 12. A gas generator for an air bag according to claim 11, wherein the fuel is a guanidine derivative or a mixture thereof.
 13. A porous tube member used in a gas generator for an air bag in which an inner cylindrical member is arranged in a cylindrical housing having a gas discharge port to define the interior of the housing, an ignition means activated upon the impact and generating a flame and/or a heat is arranged in the inner cylindrical member, a combustion chamber is provided outside the inner cylindrical member in the radial direction and stores a gas generating agent ignited and burned to generate a combustion gas due to the flame and/or the heat of the ignition means ejected from a flame-transferring hole provided on a circumferential wall of the inner cylindrical member, and a cylindrical filter means for cooling and/or purifying the combustion gas generated due to the combustion of the gas generating agent is arranged outside the combustion chamber in the radial direction, wherein the porous tube member has a shape capable of being arranged opposite to an inner peripheral surface of the cylindrical coolant/filter means and at least a portion crossing an ejecting direction of the flame and/or the heat of the ignition means ejected from the flame-transferring hole is formed as a flame-preventing annular portion having no opening.
 14. A gas generator for an air bag according to claim 13, wherein the porous tube member includes a tube portion comprising a flame-preventing annular portion having no opening and a porous annular portion having a plurality of openings, and the flame-preventing annular portion and the porous annular portion are provided adjacent to each other in the axial direction of the tube portion.
 15. A gas generator for an air bag according to claim 13 or 14, wherein the porous tube member includes a tube portion facing an inner peripheral surface of filter means and a flange portion which formed integrally with one end opening of the tube portion to have an inward shape like a flange.
 16. An air bag apparatus comprising: a gas generator for an air bag; an impact sensor detecting the impact to activate the gas generator; an air bag introducing therein a gas generated in the gas generator to inflate; and a module case storing the air bag, wherein the gas generator for the air bag is the gas generator for the air bag according to any one of claims 1 to
 12. 17. A multistage type air bag apparatus comprising: a multistage type air bag gas generator storing a plurality of electrical ignition type igniters in a housing thereof; an ignition signal outputting means provided with the outputting portions for outputting the activation signal to the igniters due to then impact as many as the igniters; and a plurality of lead wires having connectors, wherein the igniters and the outputting portions are connected by the lead wires having the connectors, and the connectors have a defining means which specifies the unique connection of the respective igniters and the respective outputting portions, and the defining means is realized by changing at least one of a shape, the number, a size, a color and a position of the connector or of the conductive portion existing in the connector.
 18. A multistage type air bag apparatus according to claim 17, wherein the conductive portion of the connector is of convex shape or concave shape, and is connected to the conductive portion of the connecting portion which is formed into a concave shape or convex shape.
 19. A multistage type air bag apparatus according to claim 17 or 18, wherein the plurality of lead wires are converged into one connector, and the connector is provided with defining means for specifying the connecting portion which can be connected to the connector.
 20. A multistage type air bag apparatus according to any one of claims 17 to 19, wherein the plurality of lead wires respectively include connectors, the plurality of connectors are connected to one another through a plastic member.
 21. A multistage type air bag apparatus according to any one of claims 17 to 20, wherein a ring member interposed between the igniter and a connector of a lead wire at a time of connecting to the connector of the lead wire is arranged in the igniter, and the defining means is formed in the ring member to specify the unique connection between the respective igniters and the respective connectors.
 22. A multistage type air bag apparatus according to claim 21, wherein the defining means is formed in the ring member and the connector.
 23. A multistage type air bag apparatus according to claim 21 or 22, wherein the defining means specifies the unique connection between the respective ring members and the respective igniters and/or the unique connection between the respective ring members and the respective connectors of the lead wires.
 24. A connector for a multistage type air bag apparatus according to any one of claims 17 to 23, the connector being used in a plurality of lead wires connecting the outputting portions to a plurality of igniters, wherein a defining means which specifies the unique connection between the respective outputting portions and the igniters is provided.
 25. A gas generator for a multistage type air bag apparatus comprising: a plurality of igniters activated by the electric signal; a gas generating means burning and/or expanding due to an activation of the igniters to generate an operating gas; the igniters and the gas generating means being stored in a housing having a gas discharge port, wherein each of the igniters has a connecting portion for joining a connector arranged at a tip end of a lead wire transmitting an activation signal outputted from an outputting portion of an ignition signal outputting means, a defining means capable of connecting only one of the connectors of a plurality of lead wires extending from the outputting portion is provided in the connecting portion, the connectors and the igniters both have conductive portions which enable the ignition-signal outputting means and the igniter to transfer to each other by connecting and contacting the connectors and the igniters, and the defining means can be realized by changing at least one of a shape, the number, a size, a color and a position of the connector or of the conductive portion existing in the connector, at the respective igniters, and/or by a positioning means provided in a flange formed on the housing
 26. A gas generator for a multistage type air bag according to claim 25, wherein the defining means comprises a connector and a connecting portion which are formed to be complementarily fitted to each other.
 27. A gas generator for a multistage type air bag according to claim 25 or 26, wherein the defining means is a groove and/or a projection which are formed in the connecting portion by changing at least one of the number, a size, a color, a position and a shape at each igniter.
 28. A gas generator for a multistage type air bag according to any one of claims 25 to 27, wherein the defining means is formed in the ring member interposed between the igniter and the connector of the lead wire at a time of connecting to the connector of the lead wire, thereby specifying the unique connection between the respective igniters and the respective connectors of the lead wires.
 29. A gas generator for a multistage type air bag according to claim 28, wherein the defining means defines the unique connection between the respective ring members and the igniters and/or the unique connection between the respective ring members and the connectors.
 30. A connector connecting method of connecting an ignition signal outputting means which includes a control unit for sending an ignition signal to a plurality of igniters included in a gas generator, and a plurality of ignition means included in the gas generator, wherein each of the igniters is connected to an outputting portion of an ignition means outputting device through a lead wire having a connector, and connections of the respective igniters and the respective outputting portions are decided by a defining means, the connectors and the igniters have conductive portions which enable the ignition-signal outputting means and the igniter to transfer to each other by connecting and contacting the connectors and the igniters, and the defining means can be realized by changing at least one of a shape, the number, a size, a color and a position of the connector or of the conductive portion existing in the connector, at the respective igniters, and/or by a positioning means provided in a flange formed on the housing.
 31. A method of connecting a connector according to claim 30, wherein the igniter includes a connecting portion for connecting to the connector, and the defining means is formed on the connecting portion of each of the igniters and the connector which connects the lead wire extending from the outputting portion to the respective igniters.
 32. A method of connecting a connector according to claim 31, wherein the defining means is the connector and the connecting portions which are formed into such shapes that they can be fitted to each other complementarily.
 33. A connector connecting method according to claim 31 or 32, wherein the defining means is a groove and/or a projection which are formed in the connecting portion by changing at least one of the number, a size, a color, a position and a shape at each of the igniters.
 34. An air bag apparatus comprising: a gas generator for an air bag which stores at least one electrical ignition type igniter in a housing; an ignition signal outputting means having outputting portions for outputting an activation signal to the igniters due to the impact as many as the igniters; and lead wires as many as the electrical ignition type igniters, the lead wires having connectors, wherein a defining means for specifying the unique connection between the respective igniters and the respective connectors of the lead wires is provided in each of the igniters.
 35. An air bag apparatus according to claim 34, wherein a ring member interposed between the igniter and the connector of the lead wire at a time of connecting to the connector of the lead wire is arranged in the igniter, and the defining means is formed in the ring member to specify the unique connection between the respective igniters and the respective connectors.
 36. An air bag apparatus according to claim 34, wherein the defining means is formed in the ring member and the connector.
 37. An air bag apparatus according to claim 35 or 36, wherein the defining means specifies the unique connection between the respective ring members and the respective igniters and/or the unique connection between the respective ring members and the respective connectors of the lead wires.
 38. A gas generator for an air bag comprising: at least one igniter activated by the electric signal; a gas generating means burning and/or expanding due to an activation of the igniter to generate an operating gas; and the igniter and the gas generating means being stored in a housing having a gas discharge port, wherein each of the igniters exposes a conductive portion, which receives the activation signal, out of the housing, and defining means for deciding unique connections between the conductive portions and the connectors of a plurality lead wires extending from the outputting portions are provided in portions from which the conductive portions are exposed.
 39. A gas generator for an air bag according to claim 38, wherein a ring member is interposed between the igniter and the connector of the lead wire at a time of connecting to the connector of the lead wire, and the defining means is formed in a portion in which the ring member is arranged in the gas generator to specify the unique connection between the respective igniters and the respective connectors.
 40. A gas generator for an air bag according to claim 39, wherein the defining member specifies the unique connection between the respective ring members and the respective igniters, thereby specifying the unique connection between the respective igniters and the respective connectors. 